The present invention relates to a method of managing a manufacturing process, such as a dispatch (priority process) for manufacturing a semiconductor device.
Patent Reference 1: Japan Unexamined Patent Application Publication No. H10-41204
Patent Reference 2: Japan Unexamined Patent Application Publication No. 2001-273023
Patent Reference 3: Japan Unexamined Patent Application Publication No. 2002-73148
The above-listed patent reference 1 discloses a manufacturing process managing system comprising a memory to register items in process for sorting them by the product type, a memory to register manufacturing devices to process the items in process for sorting them by device group of each manufacturing step, and CPU to compute the load sharing rate of those manufacturing devices.
In this manufacturing process managing system, the load sharing rate of each manufacturing device is calculated based on two assumptions. The first assumption is that the operating rate of a manufacturing device defined by the number of products scheduled to be manufactured in a unit period, the operable time of a manufacturing device in a unit period, the processing time to process items in process in a unit period, and the load sharing rate of each manufacturing device is equal to the operating rate of other manufacturing device. The second assumption is that the summation of the load sharing rates of manufacturing devices in a manufacturing device group is 1, in order to evenly allot loads to each manufacturing device. Therefore, several types of products can be manufactured fully using existing manufacturing equipment.
The patent reference 2 discloses a production managing method, whereby the manufacturing schedule can be made such that the usage rate of each manufacturing device by each step is constant during the operation period in mid-term production planning, when a group of manufacturing devices are commonly used by a group of steps.
In this production managing method, the ratio of accumulated scheduled production to accumulated capable production in the whole operating period of the mid-term production planning is calculated as the operating rate for each step. Then, the optimum usage ratio of each device is calculated such that the operating rates are equal among the steps in the group. Therefore, the calculated optimum usage ratio can reflect the short-term production planning.
The patent reference 3 discloses a production managing instrument for determining the processing number among a plurality of lots. When there are a plurality of lots to produce each product, this instrument first determines the device load ratio of each manufacturing device, which is a measure of load of the device used to process each lot, then determines the load ratio priority according to the device load ratio, and then determines the processing order by integrating the load ratio priority with another priority determined by other factor that determines a processing lot unit. Therefore, the decrease of processing ability of device due to a trouble is considered, and lowering the efficiency of the production line can be minimized.
However, many conventional manufacturing process managing systems or similar systems are designed so as to determine the priority number for processing based on the operating condition of the manufacturing device or the condition of items in process, or designed to simply process overdue items preferentially. Therefore, the operating rate of the manufacturing device is not dramatically improved, and the manufacturing time is not satisfactorily shortened.